Lugo, Spain — A cluster of picture-pretty stone homes lies at the bottom of a verdant valley here in northern Galicia, where the only sound comes from wind rustling fig and peach trees.

Called O Penso when residents lived here – the very last of whom left about a decade ago – the hamlet is now for sale, and includes a bread-making hearth, several barns, and stone and wood horreos, the raised granaries typical in this part of the country.

It has already stirred the dreams of potential buyers, including one American entrepreneur interested in turning it into a language school.

It would be the stuff of dreams were it not also the symptom of a problem clouding Galicia's future: The area is essentially dying. The Galician statistics institute warned recently that this region of northwest Spain could lose 1 million residents in the next 35 years, or roughly a third of its population.

All of Europe is rapidly aging, as women choose to have fewer children, or none at all, and immigration – despite the shrill news about a flood of migrants into Europe – has failed to reach the corners of the Continent where populations are the oldest.

Demography is quick becoming the key policy challenge of Europe's leaders, as countries scramble to figure out how to keep labor systems running and pensions paid.

But it is also having a profound impact on the physical landscape of Europe, from maternity wards and schools closing their doors, to churches being turned into art venues and leisure centers.

Here in this corner of the Iberian Peninsula, the business of selling abandoned villages has even become something of a policy tool. One mayor is trying to give away an abandoned village in his district for free, so long as “buyers” promise to restore it and add back value – ideally drawing young people while they do so.

If Galicia cannot turn back its demographic trends, says Xoaquin Fernandez Leiceaga, a former lawmaker and professor of economics at the University of Santiago de Compostela, parts of it could quickly turn into wildland.

“Already villages of Galicia are being overrun by weeds and bushes,” he says.

Economic crisis worsened long-term trends

But there is more at stake than policy and economy: identity. In an interview on the coast, far from the rural interior, Mr. Fernandez Leiceaga says that nearly all Gallegos have a piece of land handed down from their parents – himself included – and that Gallegos idealize their rural heritage. “We still have a rural mindset,” he says. Yet, “it is a world that is disappearing, with nothing to substitute it.”

When a German institute, the BBSR, released a new map recently showing population shifts in Europe, it revealed clear population declines in the Baltic countries and eastern Europe. The trends are much more dire there than in much of the rest of Europe, except for eastern Germany and the stretch of the Iberian peninsula that includes Galicia, Asturias, and northern Portugal.

These are long-term trends, but the economic crisis that hit southern Europe has played an important role – causing young people to emigrate and forgo children. The latest figures from the European Commission’s Eurostat show that while the average fertility rate in the European Union stands at 1.55 births per woman, in the hardest hit countries it is below average: 1.27 in Spain, 1.2 in Portugal, and 1.3 in Greece. Galicia’s rate stands at only about 1 birth per woman, and some years below that.

“There is nobody here,” says Matilde Fojo Fustes, a 60-year-old who runs a restaurant in the hills of Galicia near O Penso. Because the population in the immediate are has dropped from 600 to less than 50 in her lifetime, the eatery now caters mostly to loggers and summer vacationers.

Emigration began decades ago

Cleaning out his animal pens nearby, Jose Luis Gomez Picos says that when he was growing up, his hometown was a vibrant place where the residents raised cattle and cultivated potatoes, corn, and wheat. The schoolhouse closed down long ago – it is now someone’s private but shuttered home – and in the past eight years, the last of the establishments, a bar, closed its doors. “It is sad,” he says.

At 63, Mr. Gomez Picos is one of the youngest residents around. When he goes, he says, there is no one else to follow.

Spain’s National Statistics Institute estimated recently that more than half of the country’s nearly 3,000 abandoned villages are in Galicia. They emptied long before the economic crisis, with waves of emigration starting in the 1950s. But the crisis has brought even less hope that they will be revived.

The local Galician government has formed a special commission on demographics including television advertisements to urge women to have more children. The mayor in rural Cortegada, Avelino Luis de Francisco Martinez, has tried another tactic: trying to give away an abandoned village in his district for free, so long as the new owner restores the 12 vacant homes.

“They can do with it whatever they want, as long as it brings back value to the community,” he says.

400 villages to sell?

Mr. Adkinson says he has identified some 400 villages in Galicia that are abandoned and could possibly be on the market if the ownership rights were determined. He currently has clients looking at five.

The real estate of abandoned villages and rural properties is a passion as well as a job. But he also says he’s gratified to play his part in repopulation: “I feel fabulous, bringing people back into Galicia, taking people back to the land.”

If he is able to sell O Penso, at least he’ll make one person happy: Mr. Gomez Picos, who lives right up the dirt road.

“When I was younger, I’d walk around to see my cows and say ‘hello, good day,’ the whole way there,” he says. “Now there is no one to greet. No one.”